KIEV, Aug. 14 – Ukrainian investigators found the name of Donald Trump’s campaign chairman, Paul Manafort, in secret financial records indicating he may have received millions of dollars from his client, now deposed President Viktor Yanukovych, The New York Times reported Sunday.

Handwritten ledgers show $12.7 million in undisclosed cash payments designated for Manafort from Yanukovych’s pro-Russian political party from 2007 to 2012, according to Ukraine’s newly formed National Anti-Corruption Bureau.

Investigators assert that the disbursements were part of an illegal off-the-books system whose recipients also included election officials.

In addition, criminal prosecutors are investigating a group of offshore shell companies that helped members of Yanukovych’s inner circle finance their lavish lifestyles, including a palatial presidential residence with a private zoo, golf course and tennis court.

Among the hundreds of murky transactions these companies engaged in was an $18 million deal to sell Ukrainian cable television assets to a partnership put together by Manafort and a Russian oligarch, Oleg Deripaska, a close ally of President Vladimir Putin.

Manafort’s involvement with moneyed interests in Russia and Ukraine had previously come to light. But as American relationships there become a rising issue in the presidential campaign — from Trump’s favorable statements about Putin and his annexation of Crimea to the suspected Russian hacking of Democrats’ emails — an examination of Manafort’s activities offers new details of how he mixed politics and business out of public view and benefited from powerful interests now under scrutiny by the new government in Kiev.

Anti-corruption officials there say the payments earmarked for Manafort, previously unreported, are a focus of their investigation, though they have yet to determine if he actually received the cash. While Manafort is not a target in the separate inquiry of offshore activities, prosecutors say he must have realized the implications of his financial dealings.

“He understood what was happening in Ukraine,” said Vitaliy Kasko, a former senior official with the general prosecutor’s office in Kiev. “It would have to be clear to any reasonable person that the Yanukovych clan, when it came to power, was engaged in corruption.”

Manafort did not respond to interview requests or written questions from The New York Times. But his lawyer, Richard A. Hibey, said Manafort had not received “any such cash payments” described by the anti-corruption officials.

Hibey also disputed Kasko’s suggestion that Manafort might have countenanced corruption or been involved with people who took part in illegal activities.

“These are suspicions, and probably heavily politically tinged ones,” said Hibey, a member of the Washington law firm Miller & Chevalier. “It is difficult to respect any kind of allegation of the sort being made here to smear someone when there is no proof and we deny there ever could be such proof.”

Before he fled to Russia two years ago, Yanukovych and his Party of Regions relied heavily on the advice of Manafort and his firm, who helped them win several elections.

The papers, known in Ukraine as the “black ledger,” are a chicken-scratch of Cyrillic covering about 400 pages taken from books once kept in a third-floor room in the former Party of Regions headquarters on Lipska Street in Kiev. The room held two safes stuffed with $100 bills, said Taras Chornovil, a former party leader who was also a recipient of the money at times. He said in an interview that he had once received $10,000 in a “wad of cash” for a trip to Europe.

While working in Ukraine, Manafort had also positioned himself to profit from business deals that benefited from connections he had gained through his political consulting. One of them, according to court filings, involved a network of offshore companies that government investigators and independent journalists in Ukraine have said was used to launder public money and assets purportedly stolen by cronies of the government.

The network comprised shell companies whose ultimate owners were shielded by the secrecy laws of the offshore jurisdictions where they were registered, including the British Virgin Islands, Belize and the Seychelles.

The role of the offshore companies in business dealings involving Manafort came to light because of court filings in the Cayman Islands and in a federal court in Virginia related to an investment fund, Pericles Emerging Markets. Manafort and several partners started the fund in 2007, and its major backer was Deripaska, the Russian mogul, to whom the State Department has refused to issue a visa, apparently because of allegations linking him to Russian organized crime, a charge he has denied.

Deripaska agreed to commit as much as $100 million to Pericles so it could buy assets in Ukraine and Eastern Europe, including a regional cable television and communications company called Black Sea Cable. But corporate records and court filings show that it was hardly a straightforward transaction.

The Black Sea Cable assets were controlled by a rotating cast of offshore companies that led back to the Yanukovych network, including, at various times, Milltown Corporate Services and two other companies well known to law enforcement officials, Monohold A.G. and Intrahold A.G.

Those two companies won inflated contracts with a state-run agricultural company, and also acquired a business center in Kiev with a helicopter pad on the roof that would ease Yanukovych’s commute from his country estate to the presidential offices.

Deripaska would later say he invested $18.9 million in Pericles in 2008 to complete the acquisition of Black Sea Cable. But the planned purchase — including the question of who ended up with the Black Sea assets — has since become the subject of a dispute between Deripaska and Manafort.

In 2014, Deripaska filed a legal action in a Cayman Islands court seeking to recover his investment in Pericles, which is now defunct. He also said he had paid about $7.3 million in management fees to the fund over two years. Deripaska did not respond to requests for comment.

Manafort’s lawyer, Hibey, disputed the account of the Black Sea Cable deal contained in Deripaska’s Cayman filings, and said the Russian oligarch had overseen details of the final transaction involving the acquisition.

He denied that Manafort had received management fees from Pericles during its operation, but said that one of Manafort’s partners, Rick Gates, who is also working on the Trump campaign, had received a “nominal” sum.

Court papers indicate that Pericles’ only deal involved Black Sea Cable. (nt/ez)